Durable and soft wet pressed tissue

ABSTRACT

The present invention relates to soft, durable wet pressed tissue products comprising Southern softwood fibers and more particularly low-coarseness Southern softwood fibers. The inventive tissue products generally comprise little or no Northern softwood kraft fibers yet have comparable or better tissue product properties such as a TS7 value (a measure of tissue softness) less than about 20.0 dB V2 rms and a CD Durability Index (a measurement of tissue durability) greater than about 14.0.

BACKGROUND OF THE DISCLOSURE

Tissue products, such as facial tissues, paper towels, bath tissues, napkins, and other similar products, are designed with several important properties in mind. For example, the products should have good bulk, a soft feel, and should be strong and durable. Unfortunately, however, when steps are taken to increase one property of the product, other properties are often adversely affected.

To achieve the optimum product properties, tissue products are typically formed, at least in part, from pulps containing wood fibers and often a blend of hardwood and softwood fibers to achieve the desired properties. Typically when attempting to optimize surface softness, as is often the case with tissue products, the papermaker will select the fiber furnish based in part on the coarseness of pulp fibers. Pulps having fibers with low-coarseness are desirable because tissue paper made from fibers having a low-coarseness can be made softer than similar tissue paper made from fibers having a high coarseness. To optimize surface softness even further, premium tissue products usually comprise layered structures where the low-coarseness fibers are directed to the outside layer of the tissue sheet with the inner layer of the sheet comprising longer, coarser fibers.

Unfortunately, the need for softness is balanced by the need for durability. CD Durability in tissue products can be defined in terms of tensile strength, tensile energy absorption (TEA), burst strength and tear strength. Typically tear, burst and TEA will show a positive correlation with tensile strength while tensile strength, and thus durability, and softness are inversely related. Thus the paper maker is continuously challenged with the need to balance the need for softness with a need for durability. Unfortunately, tissue paper durability generally decreases as the fiber length is reduced. Therefore, simply reducing the pulp fiber length can result in an undesirable trade-off between product surface softness and product durability.

Besides durability long fibers also play an important role in overall tissue product softness. While surface softness in tissue products is an important attribute, a second element in the overall softness of a tissue sheet is stiffness. Stiffness can be measured from the tensile slope of stress—strain tensile curve. The lower the slope the lower the stiffness and the better overall softness the product will display. Stiffness and tensile strength are positively correlated, however at a given tensile strength shorter fibers will display a greater stiffness than long fibers. While not wishing to be bound by theory, it is believed that this behavior is due to the higher number of hydrogen bonds required to produce a product of a given tensile strength with short fibers than with long fibers. Thus, easily collapsible, low-coarseness long fibers, such as those provided by Northern softwood kraft (NSWK) fibers typically supply the best combination of durability and softness in tissue products when those fibers are used in combination with hardwood kraft fibers such as eucalyptus hardwood kraft fibers (EHWK). While NSWK fibers have a higher coarseness than EHWK fibers, their small cell wall thickness relative to lumen diameter combined with their long length makes them the ideal candidate for optimizing durability and softness in tissue.

Unfortunately supply of NSWK is under significant pressure both economically and environmentally. As such, prices of NSWK have escalated significantly creating a need to find alternatives to optimize softness and strength in tissue products. Alternatives, however, are limited. For example, Southern softwood kraft (SSWK) may only be used in limited amounts in the manufacture of tissue products because its high coarseness results in stiffer, harsher feeling products than NSWK. Thus, to-date SSWK is not widely used in the manufacture of premium tissue products, which must be both soft and strong.

Therefore, what is needed is a long fiber having relatively low-coarseness that may be used to manufacture a tissue product that is both soft and strong.

SUMMARY OF THE DISCLOSURE

The present inventors have surprisingly discovered that a soft and strong tissue product may be produced using a fiber furnisher comprising Southern softwood (SSW) fibers and more particularly low-coarseness Southern softwood (low-coarseness SSW) fibers and still more preferably low-coarseness Southern softwood kraft (low-coarseness SSWK) fibers. The tissue products of the present invention have properties comparable or better than those produced using conventional softwood fibers, such as Northern softwood kraft (NSWK) fibers. Accordingly, in certain preferred embodiments, SSW fibers may replace at least about 50 percent of the NSWK in the tissue product, more preferably at least about 75 percent and still more preferably all NSWK without negatively effecting the tissue product's softness and durability.

Accordingly, in certain embodiments the tissue products may comprise a multi-layered tissue web where one or more of the layers comprise low-coarseness SSW fibers and NSWK fibers and/or conventional SSWK fibers. Blending low-coarseness SSW fibers with NSWK fibers and/or conventional SSWK fibers may improve the physical properties of the tissue product, such as increased softness and durability, while reducing the cost of manufacture. Thus, in certain embodiments, the invention provides a tissue product comprising from about 5 to about 30 percent, by weight of the product, low-coarseness SSW fibers and from about 5 to about 30 percent, by weight of the product, conventional SSW fibers.

The blend of low-coarseness SSW fibers and conventional SSW fibers may be selectively incorporated into the non-skin contacting layer of a multi-layered product, such as the middle layer of a three layered tissue product. Moreover, the blend of low-coarseness SSW fibers and conventional SSW fibers may displace substantially all of the NSWK in a tissue product while improving the product properties, such as improved durability and increased softness.

In other embodiments the present invention provides for a soft and durable wet pressed tissue web comprising SSW fibers and more preferably low-coarseness SSW fibers, where the SSW fibers displace substantially all of the NSWK fibers. The inventive wet pressed tissue webs may be converted into single or multiply tissue products comprising from about 5 to about 30 percent, by weight of the product, low-coarseness SSW fibers. Thus, in one embodiment the present invention provides a multi-ply tissue product comprising at least one wet pressed tissue ply comprising from about 5 to about 30 percent, by weight of the ply, low-coarseness SSW fibers.

In still other embodiments the present invention provides a single ply wet pressed tissue product that is soft, such as a tissue product having a TS7 value less than about 20.0 dB V2 rms and more preferably less than about 18.0 dB V2 rms, such as from about 15.0 to about 20.0 dB V2 rms, and durable, such as a tissue product having a CD Durability Index greater than about 14.0 and more preferably greater than about 15.0.

In another embodiment the present invention provides a single ply wet pressed tissue product having a CD Tensile greater than about 400 g/3″, a CD Durability Index greater than about 14.0 and a TS7 value from about 15.0 to about 20.0 dB V2 rms.

In still other embodiments the present invention provides a single ply wet pressed tissue product having a GMT from about 700 to about 1100 g/3″ and more preferably from about 750 to about 900 g/3″, a CD Durability Index greater than about 14.0 and a TS7 value less than about 20.0 dB V2 rms.

In yet another embodiment the present invention provides a single ply wet pressed tissue product comprising at least about 5 percent, by weight of the product, such as from about 5 to about 30 percent, low-coarseness SSWK fibers, the tissue product having a GMT from about 700 to about 1000 g/3″, a CD Tensile greater than about 400 g/3″, a CD Durability Index greater than about 14.0 and a TS7 value less than about 20.0 dB V2 rms.

In still other embodiments the present invention provides a single ply wet pressed tissue product having improved formation, the tissue product comprising at least about 5 percent, by weight of the product, such as from about 5 to about 30 percent, low-coarseness SSWK fibers, and having a PPF value less than about 33 and a C5 value less than about 18.

Definitions

As used herein, the term “fiber length” refers to the length weighted average length of fibers determined utilizing a Kajaani fiber analyzer model No. FS-100 available from Kajaani Oy Electronics, Kajaani, Finland. According to the test procedure, a pulp sample is treated with a macerating liquid to ensure that no fiber bundles or shives are present. Each pulp sample is disintegrated into hot water and diluted to an approximately 0.001 percent solution. Individual test samples are drawn in approximately 50 to 100 ml portions from the dilute solution when tested using the standard Kajaani fiber analysis test procedure. The weighted average fiber length may be expressed by the following equation:

$\sum\limits_{x_{i} = 0}^{k}\; {\left( {x_{i} \times n_{i}} \right)\text{/}n}$

where k=maximum fiber length

-   x=fiber length -   n=number of fibers having length x_(i) -   n=total number of fibers measured.

As used herein, the term “coarseness” refers to the fiber mass per unit of unweighted fiber length reported in units of milligrams per one hundred meters of unweighted fiber length (mg/100 m) as measured using a suitable fiber coarseness measuring device such as the above mentioned Kajaani FS-200 analyzer. The coarseness of the pulp is an average of three coarseness measurements of three fiber specimens taken from the pulp. The operation of the analyzer for measuring coarseness is similar to the operation for measuring fiber length described above.

As used herein, the term “basis weight” generally refers to the bone dry weight per unit area of a tissue and is generally expressed as grams per square meter (gsm). Basis weight is measured using TAPPI test method T220. Tissue products of the present invention may be produced in a wide range of basis weights, such as from about 10 to about 60 gsm and more preferably from about 15 to about 30 gsm and in particularly preferred embodiments from about 15 to about 20 gsm.

As used herein, the term “Burst Index” refers to the dry burst peak load (typically having units of grams) at a relative geometric mean tensile strength (typically having units of g/3″) as defined by the equation:

${{Burst}\mspace{14mu} {Index}} = {\frac{{Dry}\mspace{14mu} {Burst}\mspace{14mu} {Peak}\mspace{14mu} {Load}\mspace{14mu} (g)}{{GMT}\mspace{14mu} \left( {g\text{/}3^{''}} \right)} \times 10}$

While Burst Index may vary, tissue products prepared according to the present disclosure generally have a Burst Index greater than about 5.0, more preferably greater than about 6.0 and still more preferably greater than about 7.0, such as from about 5.0 to about 8.0.

As used herein, the term “caliper” is the representative thickness of a single sheet (caliper of tissue products comprising two or more plies is the thickness of a single sheet of tissue product comprising all plies) measured in accordance with TAPPI test method T402 using an EMVECO 200-A Microgage automated micrometer (EMVECO, Inc., Newberg, Oreg.). The micrometer has an anvil diameter of 2.22 inches (56.4 mm) and an anvil pressure of 132 grams per square inch (per 6.45 square centimeters) (2.0 kPa).

As used herein, the term “CD TEA Index” refers the CD tensile energy absorption (typically having units of g·cm/cm²) at a given CD tensile strength (typically having units of g/3″) as defined by the equation:

${{CD}\mspace{14mu} {TEA}\mspace{14mu} {Index}} = {\frac{{CD}\mspace{14mu} {TEA}\mspace{14mu} \left( {{g \cdot {cm}}\text{/}{cm}\; 2} \right)}{{CDT}\mspace{14mu} \left( {g\text{/}3^{''}} \right)} \times 1\text{,}000}$

While the CD TEA Index may vary, tissue products prepared according to the present disclosure generally have a CD TEA Index greater than about 6.0, more preferably greater than about 7.0 and still more preferably greater than about 7.5, such as from about 6.0 to about 8.0.

As used herein, the term “CD Tear Index” refers to the CD Tear Strength (typically expressed in grams) at a given CD tensile strength (typically having units of g/3″) as defined by the equation:

${{CD}\mspace{14mu} {Tear}\mspace{14mu} {Index}} = {\frac{{CD}\mspace{14mu} {Tear}\mspace{14mu} (g)}{{CDT}\mspace{14mu} \left( {g\text{/}3^{''}} \right)} \times 100}$

While the CD Tear Index may vary, tissue products prepared according to the present disclosure generally have a CD Tear Index greater than about 1.5, more preferably greater than about 1.8 and still more preferably greater than about 2.0 such as from about 1.5 to about 2.5.

As used herein, the term “CD Durability Index” refers to the sum of the CD Stretch, CD Tear Index and the CD TEA Index, and is an indication of the durability of the product at a given CD tensile strength. CD Durability Index is defined by the equation:

Durability Index=CD Tear Index+CD TEA Index+CD Stretch

While the CD Durability Index may vary, tissue products prepared according to the present disclosure generally have a CD Durability Index greater than about 14.0, more preferably greater than about 14.5 and still more preferably greater than about 15.0, such as from about 14.0 to about 18.0.

As used herein, the term “machine direction (MD) tensile strength” is the peak load per 3 inches of sample width when a sample is pulled to rupture in the machine direction. Similarly, the “cross-machine direction (CD) tensile strength” is the peak load per 3 inches of sample width when a sample is pulled to rupture in the cross-machine direction. The percent elongation of the sample prior to breaking is the “stretch” and may be specified according to the orientation of the sample as either “MD stretch” or “CD stretch”. The MD tensile strength, CD tensile strength and stretch are in the course of determining tensile strength as described in the Test Methods section.

As used herein, the terms “geometric mean tensile” and “GMT” refer to the square root of the product of the machine direction tensile strength and the cross-machine direction tensile strength of the tissue product. While the GMT may vary, tissue products prepared according to the present disclosure generally have a GMT greater than about 700 g/3″, more preferably greater than about 750 g/3″ and still more preferably greater than about 800 g/3″, such as from about 700 to about 1200 g/3″.

As used herein, the term “layer” refers to a plurality of strata of fibers, chemical treatments, or the like within a ply.

As used herein, the terms “layered tissue web,” “multi-layered tissue web,” “multi-layered web,” and “multi-layered paper sheet,” generally refer to sheets of paper prepared from two or more layers of aqueous papermaking furnish which are preferably comprised of different fiber types. The layers are preferably formed from the deposition of separate streams of dilute fiber slurries, upon one or more endless foraminous screens. If the individual layers are initially formed on separate foraminous screens, the layers are subsequently combined (while wet) to form a layered composite web.

The term “ply” refers to a discrete product element. Individual plies may be arranged in juxtaposition to each other. The term may refer to a plurality of web-like components such as in a multi-ply facial tissue, bath tissue, paper towel, wipe, or napkin.

As used herein, the term “slope” refers to slope of the line resulting from plotting tensile versus stretch and is an output of the MTS TestWorks™ in the course of determining the tensile strength as described in the Test Methods section herein. Slope is reported in the units of grams (g) per unit of sample width (inches) and is measured as the gradient of the least-squares line fitted to the load-corrected strain points falling between a specimen-generated force of 70 to 157 grams (0.687 to 1.540 N) divided by the specimen width. Slopes are generally reported herein as having units of grams (g).

As used herein, the term “geometric mean slope” (GM Slope) generally refers to the square root of the product of machine direction slope and cross-machine direction slope. GM Slope generally is expressed in units of kilograms (kg).

As used herein, the term “low-coarseness Southern softwood” (low-coarseness SSW) refers to a fiber derived from a pine in the Pinus subgenus including, for example, P. taeda, P. elliotti, P. palustris, P. pungens, P. rigida, P. serotina, P. muricata and P. radiate, the fiber having a coarseness less than about 21 mg/100 m, such as from about 16 to about 21 mg/100 m, and more preferably from about 17 to about 20.5 mg/100 m, and a fiber length from about 2.0 to about 3.0 mm, and more preferably from about 2.2 to about 2.7 mm.

As used herein, the term “Stiffness Index” refers to GM Slope (typically having units of kg), divided by GMT (typically having units of g/3″).

${{Stiffness}\mspace{14mu} {Index}} = {\frac{\sqrt{{MD}\mspace{14mu} {Tensile}\mspace{14mu} {Slope}\mspace{14mu} ({kg}) \times {CD}\mspace{14mu} {Tensile}\mspace{14mu} {Slope}\mspace{14mu} ({kg})}}{{GMT}\mspace{14mu} \left( {g\text{/}3^{''}} \right)} \times 1\text{,}000}$

While the Stiffness Index may vary, tissue products prepared according to the present disclosure generally have a Stiffness Index less than about 25.0.

As used herein, the term “sheet bulk” refers to the quotient of the caliper (generally having units of μm) divided by the bone dry basis weight (generally having units of gsm). The resulting sheet bulk is expressed in cubic centimeters per gram (cc/g). Tissue products prepared according to the present invention generally have a sheet bulk greater than about 6 cc/g, more preferably greater than about 8 cc/g such as from about 6 to about 10 cc/g.

As used herein, the terms “T57” and “TS7 value” refer to the output of the EMTEC Tissue Softness Analyzer (commercially available from Emtec Electronic GmbH, Leipzig, Germany) as described in the Test Methods section. TS7 has units of dB V2 rms, however, TS7 may be referred to herein without reference to units.

As used herein, a “tissue product” generally refers to various paper products, such as facial tissue, bath tissue, paper towels, napkins, and the like.

As used herein the formation measurement values “PPF” and “C5” refer to the output of the Paper PerFect Formation Analyzer (commercially available from OpTest Equipment Inc., Hawkesbury Ontario). The results of the formation analysis are expressed relative to perfect paper formation, the PPF value, and the formation value as measured in the range from about 2.6 to about 4.5 mm ('C5″). The test method is described in detail in U.S. Pat. No. 6,301,373, the contents of which are incorporated herein in a manner consistent with the present disclosure.

As used herein the term “wet-pressed tissue” generally refers to a tissue product manufactured by a conventional wet-pressed method in which prior to the nascent tissue web being transferred to the surface of a rotating drying cylinder, such as a Yankee dryer, water is expressed from the web and absorbed by a felt. The dewatered web, typically having a consistency of about 40 percent, is then dried while on the hot surface of the dryer. The web is then creped from the surface of the dryer.

DETAILED DESCRIPTION OF THE DISCLOSURE

It has now been discovered that manufacturing wet-pressed tissue products using Southern softwood kraft (“SSWK”) may improve softness without compromising perceived in-use strength, particularly in the CD direction of the sheet, compared to comparable products manufactured with Northern softwood kraft (“NSWK”). Having improved CD properties at a given tensile strength, the tissue products of the present disclosure have improved cross-machine durability and toughness.

Thus, in certain embodiments the present disclosure relates to tissue products, and more particularly single ply wet pressed tissue products, comprising Southern softwood (SSW) fibers and more preferably low-coarseness SSW fibers. The SSW fibers used in the manufacture of the inventive tissue products may displace a portion, and in certain embodiments all, of the long fiber length fibers, such as NSWK fibers, without significantly impairing important tissue physical properties such as durability, strength and softness. For example, in certain embodiments the inventive tissue products comprise low-coarseness SSW fibers and less than about 5 percent, by weight of the tissue product,

NSWK, yet have improved durability and softness relative to a comparable tissue product comprising 20 percent NSWK. Even more surprising is that in certain embodiments NSWK may be entirely replaced by low-coarseness SSWK fibers and the tissue product properties may be improved.

The ability to replace a significant amount of NSWK, and in certain embodiments all of the NSWK, with SSW and maintain or improve tissue product properties is surprising provided that SSW has traditionally been unsuitable for use in manufacturing premium tissue products because of its high coarseness. However, it has now been discovered that a SSW having reduced coarseness may be used in the manufacture of soft and strong tissue products. The discovery is particularly surprising because the reduction in fiber coarseness is only moderate, such as less than about 10 percent, compared to conventional SSWK. While being reduced relative to conventional SSWK, the coarseness of low-coarseness SSW fibers is still greater than NSWK as can be seen in Table 1, below.

TABLE 1 Fiber Length Coarseness Fiber Type (mm) (mg/100 m) Conventional SSWK 2.35 21.3 Low-coarseness SSWK 2.53 19.3 NSWK Pulp Fiber 2.25 14.8 Eucalyptus Kraft Pulp Fiber 0.76 8.95

While the low-coarseness SSW fibers are higher in coarseness compared to NSWK fibers they may replace NSWK fibers in tissue products without impairing important physical properties such as durability, strength and softness. Even more surprisingly, in certain embodiments, substitution of NSWK fibers with low-coarseness SSW fibers may actually increase softness (measured as TS7) while also maintaining or improving durability (measured as CD Durability Index).

The surprising increase in softness without a corresponding decrease in durability is not found in prior art single ply wet pressed tissue products. With reference to Table 2, below, tissue products of the present disclosure generally have comparable or improved durability at a given tensile strength compared to commercially available single ply wet pressed tissue products. In addition to having comparable or better durability, the instant tissue products are of comparable softness (measured as TS7).

TABLE 2 CD CD CD CD GMT CDT CDS CD TEA TEA Tear Tear Burst Burst Durability Product (g/3″) (g/3″) (%) (g * cm/cm²) Index (g) Index (g) Index Index TS7 Great Value ™ 668 458 4.4 3.04 6.638 11.04 2.41 430 6.44 13.4 22.3 1000 Family Dollar ™ 714 488 4.5 2.79 5.717 10.1 2.07 420 5.88 12.3 18.6 1000 Scott ™ 1000 889 582 5.1 4.28 7.354 9.98 1.71 488 5.49 14.2 18.6 Inventive 826 523 5.3 3.88 7.419 11 2.10 538 6.51 14.8 19.2

Thus, the instant tissue products are generally soft, having a TS7 value less than about 20.0, and durable, such as a product having a CD Durability Index greater than about 14.0, more preferably greater than about 14.5 and still more preferably greater than about 15.0, such as from about 14.0 to about 18.0. The foregoing values are generally achieved at relatively modest tensile strengths, such as from a GMT from about 700 to about 1000 g/3″ and a CD tensile strength greater than about 400 g/3″, such as from about 400 to about 800 g/3″ and more preferably from about 450 to about 600 g/3″. Moreover, in a particularly preferred embodiment, the tissue products have relatively low basis weights, such as less than about 20 gsm, such as from about 10 to about 20 gsm and more preferably from about 12 to about 18 gsm.

Accordingly, in one embodiment the present invention provides a wet pressed tissue product comprising at least about 10 percent, by weight, SSWK and more preferably low-coarseness SSWK, the tissue product having a CD Tensile from about 400 to about 600 g/3″, a CD Durability Index greater than about 14.0 and a TS7 less than about 20.0. In a particularly preferred embodiment the foregoing tissue product is produced without the addition of NSWK, thus the resulting tissue product is substantially free of NSWK, but has softness and durability comparable or better than a similar tissue product comprising NSWK.

In other embodiments the tissue product comprises a single ply wet pressed tissue product comprising less than about 5 percent, by weight of the tissue product, NSWK, the tissue product having a TS7 value from about 16.0 to about 20.0, a CD tensile greater than about 450 g/3″ and a CD Durability

Index from about 14.0 and more preferably greater than about 14.5 and still more preferably greater than about 15.0. In still other embodiments the invention provides a single ply wet pressed tissue product comprising from about 10 to about 40 percent, by weight of the web, SSW fibers, the tissue product having a TS7 from about 16.0 to about 20.0, a CD tensile greater than about 450 g/3″ and a CD Durability Index from about 14.0 to about 18.0.

In still other embodiments the single ply wet pressed tissue products of the present invention have a CD stretch from about 4.0 to about 6.0 percent, a CD TEA from about 4.0 to about 6.0 (g·cm/cm²) and a CD Tensile from about 400 to about 600 g/3″. In still other embodiments the tissue products have a CD Tear greater than about 10 g, such as from about 10 to about 12 g at a CD Tensile strength greater than about 400 g/3″, such as from about 400 to about 600 g/3″.

Not only do the instant tissue webs and products have improved durability and softness, but may also display improved formation. The improved formation of the instant webs is surprising as formation tends to correlate with fiber length and coarseness with furnishes having shorter fiber lengths and lower coarseness having better formation. Here however, substitution of NSWK with low-coarseness SSWK may actually improve formation despite the low coarseness and longer fiber length relative to

NSWK. For example, in certain embodiments the use of low-coarseness SSWK may improve formation, compared to a comparable web substantially free from low-coarseness SSWK, by at least about 10 percent and more preferably by at least about 15 percent when measured as PPF. Accordingly, in one embodiment the present invention provides a single ply wet pressed tissue product comprising less than about 5 percent, by weight of the tissue product, NSWK, the tissue product having a PPF greater than about 30 and still more preferably greater than about 32 and a C5 value greater than about 17 and more preferably greater than about 18.

In a particularly preferred embodiment the tissue product comprises a multi-layered wet pressed tissue web wherein low-coarseness SSW fiber is selectively disposed in only one of the layers such that the low-coarseness SSW fiber is not brought into contact with the user's skin in-use. For example, in one embodiment the tissue web may comprise a two layered web wherein the first layer consists essentially of hardwood kraft pulp fibers and is substantially free of low-coarseness SSWK and the second layer comprises low-coarseness SSW, wherein the low-coarseness SSWK comprises at least about 50 percent by weight of the second layer, such as from about 50 to about 100 percent by weight of the second layer. It should be understood that, when referring to a layer that is substantially free of low-coarseness SSW fibers, negligible amounts of the fiber may be present therein, however, such small amounts often arise from the low-coarseness SSW fibers applied to an adjacent layer, and do not typically substantially affect the softness or other physical characteristics of the web.

The tissue webs may be incorporated into tissue products that may be either single or multi-ply, where one or more of the plies may be formed by a multi-layered tissue web having low-coarseness SSW fibers selectively incorporated in one of its layers. In one embodiment the tissue product is constructed such that the low-coarseness SSW fibers are not brought into contact with the user's skin in-use. For example, the tissue product may comprise two wet pressed tissue webs wherein each web comprises a first fibrous layer substantially free from low-coarseness SSW fibers and a second fibrous layer comprising low-coarseness SSW fibers. The webs are plied together such that the outer surface of the tissue product is formed from the first fibrous layers of each web and the second fibrous layer comprising the low-coarseness SSW fibers is not brought into contact with the user's skin in-use.

In those embodiments where the inventive wet pressed webs are converted into multi-ply products the products may comprise two, three or four plies where at least one of the plies comprise low-coarseness SSW fibers and have comparable or better durability and softness compared to a comparable web comprising NSWK. The multi-ply tissue products may have a basis weight greater than about 20 gsm, such as from about 20 to about 60 gsm and more preferably from about 30 to about 40 gsm.

Generally low-coarseness SSW fibers useful in the present invention are derived from pines in the Pinus subgenus. Suitable species within the Pinus subgenus include, for example, P. taeda, P. elliotti, P. palustris, P. pungens, P. rigida, P. serotina, P. muricata and P. radiata. Particularly preferred are P. taeda, P. elliotti, and P. palustris. Further, it is to be understood that the compositions disclosed herein are not limited to containing any one species of low-coarseness SSW fiber and may comprise a blend of low-coarseness SSW fibers derived from two or more species, such as a blend of fibers derived from P. taeda, P. elliotti, and P. palustris.

In certain embodiments the low-coarseness SSW fibers are derived from pines within the Pinus subgenus which are less than about 14 years old and more preferably less than about 12 and still more preferably less than about 10 years, such as from about 8 to about 12 years. Generally pines within the

Pinus subgenus less than 14 years old comprise a large percentage of juvenile wood and as such have fibers with lower coarseness relative to more mature pines. In other embodiments low-coarseness SSW fibers are derived from the corewood portion of the tree, i.e., the portion of the tree comprising the first 10 to 12 growth layers from the pith. Corewood may be produced by selectively removing the outer portion of the tree, such as by removing the corewood, or by selecting the top portion of the tree which is generally less than about 10 to 12 growth layers from pith to bark.

Once the appropriate fiber source is identified suitable low-coarseness SSW fiber may be produced by any appropriate method known in the art. In one embodiment low-coarseness SSW fiber is produced by well-known chemical pulping methods such as kraft, sulfite or soda/AQ pulping methods. In one preferred embodiment low-coarseness SSW fibers are produced by kraft pulping and have a fiber length greater than about 2.2 mm and more preferably greater than about 2.4 mm, such as from about 2.2 to about 2.8 mm. Further, the foregoing fibers preferably have a coarseness less than about 21 mg/100 m, such as from about 16 to about 21 mg/100 m, more preferably from about 17 to about 20.5 mg/ 100 m and still more preferably from about 18 to about 19.5 mg/100 m.

In a particularly preferred embodiment low-coarseness SSW fibers are utilized in the tissue web as a replacement for high fiber length wood fibers such as softwood fibers and more specifically NSWK. In one particular embodiment the low-coarseness SSW fibers are substituted for NSWK such that the total amount of NSWK, by weight of the tissue product, is less than about 10 percent and more preferably less than about 5 percent. In other embodiments it may be desirable to replace all of the NSWK with low-coarseness SSW fibers such that the tissue product is substantially free from NSWK. In other embodiments low-coarseness SSW fibers may be blended with conventional SSW fibers and the blended SSW fibers may be substituted for NSWK such that the total amount of NSWK, by weight of the tissue product, is less than about 10 percent and more preferably less than about 5 percent. The blend of low-coarseness SSW fibers and conventional SSW fibers may be such that the tissue product comprises, by weight of the tissue product, from about 5 to about 30 percent low-coarseness SSW fibers and from about 5 to about 30 percent conventional SSW fibers.

Generally the base webs and tissue products of the present disclosure are prepared by a conventional wet pressed tissue manufacture. For example, tissue webs may be manufactured using a twin wire machine comprising a wet end and a dry section. The wet end includes a headbox, a movable carrying forming wire, a movable covering forming wire and a forming roll which may be perforated and provided with suction means. Alternatively, the forming roll may be smooth. The headbox supplies a single or multi-layer flow of stock between the two moving forming wires for forming a paper web by dewatering the stock. The two forming wires run together over the forming roll and then in individual loops over a plurality of rolls arranged to impel, guide, align and stretch the carrying forming wire and the covering forming wire. The rolls defining the path of the covering forming wire include a breast roll and, a short way after the forming roll, a guide roll which can be termed a forward drive roll. The covering forming wire leaves the carrying forming wire and the paper web either immediately before the wire and paper web diverge from the forming roll, or at a transfer suction box, not shown, or other transfer means located between the forming roll and forward drive roll. The carrying forming wire runs to the drying section where it leaves the paper web by changing its direction of travel around a guide roll.

The drying section comprises a Yankee dryer having a relatively large diameter and a polished cylindrical surface. The Yankee dryer, preferably consisting of a cylinder covered by a hood, in which hot air is blown at high speed against the paper web. The paper web is creped from the Yankee dryer by means of a creping doctor blade to obtain the desired creping, after which the finished creped paper web is wound onto a roll. Further, the drying section includes a felt disposed upstream of the Yankee dryer and travelling in a loop around several rolls and around a pick-up means, suitably in the form of a roll, located nearest the wet end and thereby in the vicinity of said guide roll for the carrying forming wire, and a press roll which presses against the Yankee dryer and is provided with suction means to dewater the paper web before the latter comes into contact with the Yankee dryer. The pick-up means may alternatively consist of a shoe. Further, two guide rolls are disposed between the pick-up roll and press roll, said guide rolls deflecting with a small angle the direction of travel of the felt. A blind-drilled roll is disposed after the press roll, in contact with the Yankee dryer. The paper web is transferred to the felt at the point where this and the carrying forming wire converge at the pick-up roll and thereafter immediately diverge from each other.

As described above the web is mechanically dewatered by a compression nip while the wet web is in contact with a papermaking felt and thereafter dried with the aid of a Yankee dryer. As used herein, a “felt” is an absorbent papermaking fabric designed to absorb water and remove it from a tissue web. Papermaking felts of various designs are well known in the art. The water expressed from the wet web during compression is absorbed and carried away by the felt. Commonly, the compression nip is formed between a press roll and the surface of the Yankee dryer. Particularly suitable wet-pressed tissue products in accordance with this invention are mechanically dewatered, final-dried on a Yankee dryer and once-creped.

Preferably the formed web is dried by transfer to the surface of a rotatable heated dryer drum, such as a Yankee dryer. In accordance with the present disclosure, the creping composition may be applied topically to the tissue web while the web is traveling on the fabric or may be applied to the surface of the dryer drum for transfer onto one side of the tissue web. In this manner, the creping composition is used to adhere the tissue web to the dryer drum. In this embodiment, as the web is carried through a portion of the rotational path of the dryer surface, heat is imparted to the web causing most of the moisture contained within the web to be evaporated. The web is then removed from the dryer drum by a creping blade. Creping the web, as it is formed, further reduces internal bonding within the web and increases softness. Applying the creping composition to the web during creping, on the other hand, may increase the strength of the web.

In a particularly preferred embodiment the formed web is transferred to the surface of the Yankee dryer by a suction pressure roll. Particularly suitable press loads for purposes of this invention can have a peak pressure of about 1.4 MPa or greater, more specifically from about 4 to about 8 MPa, and still more specifically from about 4 to about 6 MPa. The wet tissue web can be dewatered to a consistency of about 30 percent or greater, more specifically about 40 percent or greater, more specifically from about 40 to about 50 percent, and still more specifically from about 45 to about 50 percent. As used herein and well understood in the art, “consistency” refers to the bone dry weight percent of the web based on fiber.

In order to adhere the web to the surface of the dryer drum, a creping adhesive may be applied to the surface of the dryer drum by a spraying device. The spraying device may emit a creping composition made in accordance with the present disclosure or may emit a conventional creping adhesive. The web is adhered to the surface of the dryer drum and then creped from the drum using the creping blade. If desired, the dryer drum may be associated with a hood. The hood may be used to force air against or through the web.

Test Methods Tissue Softness

Tissue softness was measured using an EMTEC Tissue Softness Analyzer (“TSA”) (Emtec

Electronic GmbH, Leipzig, Germany). The TSA comprises a rotor with vertical blades which rotate on the test piece applying a defined contact pressure. Contact between the vertical blades and the test piece creates vibrations, which are sensed by a vibration sensor. The sensor then transmits a signal to a PC for processing and display. The signal is displayed as a frequency spectrum. For measurement of TS7 values the blades are pressed against the sample with a load of 100 mN and the rotational speed of the blades is 2 revolutions per second.

The frequency analysis in the range of approximately 200 to 1000 Hz represents the surface smoothness or texture of the test piece. A high amplitude peak correlates to a rougher surface. A further peak in the frequency range between 6 and 7 kHZ represents the softness of the test piece. The peak in the frequency range between 6 and 7 kHZ is herein referred to as the TS7 Softness Value and is expressed as dB V2 rms. The lower the amplitude of the peak occurring between 6 and 7 kHZ, the softer the test piece.

Test samples were prepared by cutting a circular sample having a diameter of 112.8 mm. All samples were allowed to equilibrate at TAPPI standard temperature and humidity conditions for at least 24 hours prior to completing the TSA testing. Only one ply of tissue is tested. Multi-ply samples are separated into individual plies for testing. The sample is placed in the TSA with the softer (dryer or Yankee) side of the sample facing upward. The sample is secured and the measurements are started via the PC. The PC records, processes and stores all of the data according to standard TSA protocol. The reported values are the average of five replicates, each one with a new sample.

Sheet Bulk

Sheet Bulk is calculated as the quotient of the dry sheet caliper (μm) divided by the basis weight (gsm). Dry sheet caliper is the measurement of the thickness of a single tissue sheet measured in accordance with TAPPI test methods T402 and T411 om-89. The micrometer used for carrying out T411 om-89 is an Emveco 200-A Tissue Caliper Tester (Emveco, Inc., Newberg, Oreg.). The micrometer has a load of 2 kilo-Pascals, a pressure foot area of 2500 square millimeters, a pressure foot diameter of 56.42 millimeters, a dwell time of 3 seconds and a lowering rate of 0.8 millimeters per second.

Tear

Tear testing was carried out in accordance with TAPPI test method T414 “Internal Tearing Resistance of Paper (Elmendorf-type method)” using a falling pendulum instrument such as Lorentzen & Wettre Model SE 009. Tear strength is directional and MD and CD tear are measured independently.

More particularly, a rectangular test specimen of the sample to be tested is cut out of the tissue product or tissue basesheet such that the test specimen measures 63 mm ±0.15 mm (2.5 inches ±0.006″) in the direction to be tested (such as the MD or CD direction) and between 73 and 114 millimeters (2.9 and 4.6 inches) in the other direction. The specimen edges must be cut parallel and perpendicular to the testing direction (not skewed). Any suitable cutting device, capable of the prescribed precision and accuracy, can be used. The test specimen should be taken from areas of the sample that are free of folds, wrinkles, crimp lines, perforations or any other distortions that would make the test specimen abnormal from the rest of the material.

The number of plies or sheets to test is determined based on the number of plies or sheets required for the test results to fall between 20 to 80 percent on the linear range scale of the tear tester and more preferably between 20 to 60 percent of the linear range scale of the tear tester. The sample preferably should be cut no closer than 6 mm (0.25 inch) from the edge of the material from which the specimens will be cut. When testing requires more than one sheet or ply the sheets are placed facing in the same direction.

The test specimen is then placed between the clamps of the falling pendulum apparatus with the edge of the specimen aligned with the front edge of the clamp. The clamps are closed and a 20-millimeter slit is cut into the leading edge of the specimen usually by a cutting knife attached to the instrument. For example, on the Lorentzen & Wettre Model SE 009 the slit is created by pushing down on the cutting knife lever until it reaches its stop. The slit should be clean with no tears or nicks as this slit will serve to start the tear during the subsequent test.

The pendulum is released and the tear value, which is the force required to completely tear the test specimen, is recorded. The test is repeated a total of ten times for each sample and the average of the ten readings reported as the tear strength. Tear strength is reported in units of grams of force (gf). The average tear value is the tear strength for the direction (MD or CD) tested. The “geometric mean tear strength” is the square root of the product of the average MD tear strength and the average CD tear strength. The Lorentzen & Wettre Model SE 009 has a setting for the number of plies tested. Some testers may need to have the reported tear strength multiplied by a factor to give a per ply tear strength. For basesheets intended to be multiple ply products, the tear results are reported as the tear of the multiple ply product and not the single ply basesheet. This is done by multiplying the single ply basesheet tear value by the number of plies in the finished product. Similarly, multiple ply finished product data for tear is presented as the tear strength for the finished product sheet and not the individual plies. A variety of means can be used to calculate but in general will be done by inputting the number of sheets to be tested rather than number of plies to be tested into the measuring device. For example, two sheets would be two 1-ply sheets for 1-ply product and two 2-ply sheets (4-plies) for 2-ply products.

Tensile

Tensile testing was done in accordance with TAPPI test method T576 “Tensile properties of towel and tissue products (using constant rate of elongation)” wherein the testing is conducted on a tensile testing machine maintaining a constant rate of elongation and the width of each specimen tested is 3 inches. More specifically, samples for dry tensile strength testing were prepared by cutting a 3±0.05 inches (76.2±1.3 mm) wide strip in either the machine direction (MD) or cross-machine direction (CD) orientation using a JDC Precision Sample Cutter (Thwing-Albert Instrument Company, Philadelphia, Pa., Model No. JDC 3-10, Serial No. 37333) or equivalent. The instrument used for measuring tensile strengths was an MTS Systems Sintech 11S, Serial No. 6233. The data acquisition software was an MTS TestWorks® for Windows Ver. 3.10 (MTS Systems Corp., Research Triangle Park, N.C.). The load cell was selected from either a 50 Newton or 100 Newton maximum, depending on the strength of the sample being tested, such that the majority of peak load values fall between 10 to 90 percent of the load cell's full scale value. The gauge length between jaws was 4±0.04 inches (101.6±1 mm) for facial tissue and towels and 2±0.02 inches (50.8±0.5 mm) for bath tissue. The crosshead speed was 10±0.4 inches/min (254±1 mm/min), and the break sensitivity was set at 65 percent. The sample was placed in the jaws of the instrument, centered both vertically and horizontally. The test was then started and ended when the specimen broke. The peak load was recorded as either the “MD tensile strength” or the “CD tensile strength” of the specimen depending on direction of the sample being tested.

Ten representative specimens were tested for each product or sheet and the arithmetic average of all individual specimen tests was recorded as the appropriate MD or CD tensile strength of the product or sheet in units of grams of force per 3 inches of sample. The geometric mean tensile (GMT) strength was calculated and is expressed as grams-force per 3 inches of sample width. Tensile energy absorbed (TEA) and slope are also calculated by the tensile tester. TEA is reported in units of g·cm/cm². Slope is recorded in units of kg. Both TEA and Slope are directional dependent and thus MD and CD directions are measured independently. Geometric mean TEA and geometric mean slope are defined as the square root of the product of the representative MD and CD values for the given property.

Multi-ply products were tested as multi-ply products and results represent the tensile strength of the total product. For example, a 2-ply product was tested as a 2-ply product and recorded as such. A basesheet intended to be used for a 2-ply product was tested as two plies and the tensile recorded as such. Alternatively, a single ply may be tested and the result multiplied by the number of plies in the final product to get the tensile strength.

Burst Strength

Burst strength herein is a measure of the ability of a fibrous structure to absorb energy, when subjected to deformation normal to the plane of the fibrous structure. Burst strength may be measured in general accordance with ASTM D-6548 with the exception that the testing is done on a Constant-Rate-of-Extension (MTS Systems Corporation, Eden Prairie, Minn.) tensile tester with a computer-based data acquisition and frame control system, where the load cell is positioned above the specimen clamp such that the penetration member is lowered into the test specimen causing it to rupture. The arrangement of the load cell and the specimen is opposite that illustrated in FIG. 1 of ASTM D-6548. The penetration assembly consists of a semi spherical anodized aluminum penetration member having a diameter of 1.588±0.005 cm affixed to an adjustable rod having a ball end socket. The test specimen is secured in a specimen clamp consisting of upper and lower concentric rings of aluminum between which the sample is held firmly by mechanical clamping during testing. The specimen clamping rings has an internal diameter of 8.89±0.03 cm.

The tensile tester is set up such that the crosshead speed is 15.2 cm/min, the probe separation is 104 mm, the break sensitivity is 60 percent and the slack compensation is 10 gf and the instrument is calibrated according to the manufacturer's instructions.

Samples are conditioned under TAPPI conditions and cut into 127×127 mm±5 mm squares. For each test a total of 3 sheets of product are combined. The sheets are stacked on top of one another in a manner such that the machine direction of the sheets is aligned. Where samples comprise multiple plies, the plies are not separated for testing. In each instance the test sample comprises 3 sheets of product. For example, if the product is a 2-ply tissue product, 3 sheets of product, totaling 6 plies are tested. If the product is a single ply tissue product, then 3 sheets of product totaling 3 plies are tested.

Prior to testing the height of the probe is adjusted as necessary by inserting the burst fixture into the bottom of the tensile tester and lowering the probe until it was positioned approximately 12.7 mm above the alignment plate. The length of the probe is then adjusted until it rests in the recessed area of the alignment plate when lowered.

It is recommended to use a load cell in which the majority of the peak load results fall between 10 and 90 percent of the capacity of the load cell. To determine the most appropriate load cell for testing, samples are initially tested to determine peak load. If peak load is <450 gf a 10 Newton load cell is used, if peak load is >450 gf a 50 Newton load cell is used.

Once the apparatus is set-up and a load cell selected, samples are tested by inserting the sample into the specimen clamp and clamping the test sample in place. The test sequence is then activated, causing the penetration assembly to be lowered at the rate and distance specified above.

Upon rupture of the test specimen by the penetration assembly the measured resistance to penetration force is displayed and recorded. The specimen clamp is then released to remove the sample and ready the apparatus for the next test.

The peak load (gf) and energy to peak (g-cm) are recorded and the process repeated for all remaining specimens. A minimum of five specimens are tested per sample and the peak load average of five tests is reported as the burst strength.

Opacity

Opacity was measured using a TECHNIBRITE Micro TB-1C testing instrument, available from Technidyne Corporation, New Albany, IND according to the manufacturer's instructions and is reported as ISO Opacity (%).

Formation

Tissue web and product formation was measured using the PaperPerFect Formation (PPF) Analyzer (OpTest Equipment Inc. Ontario, Canada). The PaperPerFect analyzer is a light-transmission formation meter and is capable of measuring the formation scale of paper ranging from 0.5 to 60 mm. The PPF analyzer measures the formation characteristics of a sample by partitioning the sample into its components as a function of scale of formation, over scale of formation range indicated above. In making the measurement, the instrument uses Fourier Transform-based power spectrum analysis in partitioning the intensity of the non-uniformity of the formation into its components as a function of the scale of formation. Normally, a 256 by 256 pixel image is extracted from the original sample, and subjected to the mirroring and Fast Fourier Transform (FFT) subroutines of the machine. The machine then provides wavelength numbers which directly relate to the dimension of the local non-uniformity in the plane of the sheet. The results are then expressed as PPF Formation Values (PPF) which are relative to a “perfect paper” (having formation value of 1000 at each component, e.g. different C size range)” and C5 value, which measures formation in the range from 2.6 to 4.5 mm.

EXAMPLES

A blended single ply wet pressed tissue product was produced from various fiber furnishes including, eucalyptus hardwood kraft (EHWK), NSWK, conventional SSWK and low-coarseness SSWK (“LC SSWK). The NSWK had a length-weighted fiber length of about 2.25 mm and a fiber coarseness of about 14.8 mg/100 m. The low-coarseness SSWK had a length-weighted fiber length of about 2.5 mm and a fiber coarseness of about 19 mg/100 m. Starch and/or refining was used to control the target geometric mean tensile strength of the resulting product. The furnish blends and target strengths are summarized in Table 3, below.

TABLE 3 Sample Furnish (wt %) 7 68% EHWK/20% NSWK/12% SSWK 8 68% EHWK/20% LC SSWK/12% SSWK 9 68% EHWK/32% LC SSWK

The stock solutions were pumped to a headbox after dilution to 0.75 percent consistency to form a blended tissue web comprising 80 percent EHWK and 20 percent softwood kraft, either NSWK or LC

SSWK. The target basis weight for all codes was about 16 gsm. The formed web was pressed against a Yankee dryer and adhered thereto using a mixture of polyvinyl alcohol, water and Kymene®. The dried web was subsequently removed from the Yankee dryer by creping. The crepe ratio was set at 1.20-1.25.

To produce one-ply tissue product, the base sheets, produced above, were calendared using a steel-on-rubber roll combination (40 P&J hardness rubber roll) to a thickness of 6.6±1.1 mils and the product wound into bath-tissue rolls of constant firmness, diameter and sheet count. The resulting one-ply tissue products were tested and exhibited the properties as shown in the tables below.

The effect of LC SSWK fibers on various tissue product strength and durability properties is summarized in the tables below.

TABLE 4 Basis Weight GMT Sheet Bulk ISO Opacity Sample (gsm) (g/3″) (g/cm³) (%) PPF C5 7 16.7 918 6.6 45.42 30.8 16.4 8 17.1 779 6.6 45.28 33.2 18.4 9 16.9 826 6.5 45.19 32.5 17.2

TABLE 5 CD CD Tensile Stretch CD Tear CD TEA GM Slope Burst Sample (g/3″) (%) (g) (g * cm/cm²) (kg) (g) 7 592 5.11 12.87 4.280 14.1 578 8 522 5.22 9.19 3.731 12.1 479 9 523 5.32 10.98 3.888 13.0 538

TABLE 6 CD CD Tear TEA Burst CD Durability Stiffness TS7 Sample Index Index Index Index Index (dB V2 rms) 7 2.17 7.23 6.30 14.51 24.96 18.74 8 1.76 7.15 6.15 14.13 22.75 18.12 9 2.10 7.43 6.51 14.85 24.51 19.19

While tissue webs, and tissue products comprising the same, have been described in detail with respect to the specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the present invention should be assessed as that of the appended claims and any equivalents thereto and the foregoing embodiments:

In a first embodiment the present invention provides a single ply wet pressed tissue product having a TS7 value less than about 20.0 dB V2 rms, a CD Tensile strength greater than about 400 g/3” and a CD Durability Index greater than about greater than about 14.0, more preferably greater than about 14.5 and still more preferably greater than about 15.0, such as from about 14.0 to about 20.0.

In a second embodiment the present invention provides the tissue product of the first embodiment having a Burst Index greater than about 5.0.

In a third embodiment the present invention provides the tissue product of the first or the second embodiments having a CD TEA Index greater than about 6.0.

In a fourth embodiment the present invention provides the tissue product of any one of the first through the third embodiments having a CD Durability Index greater than about 15.0.

In a fifth embodiment the present invention provides the tissue product of any one of the first through the fourth embodiments wherein the TS7 value is from about 18.0 to about 20.0 dB V2 rm.

In a sixth embodiment the present invention provides the tissue product of any one of the first through the fifth embodiments having a GMT from about 700 to about 1200 g/3″ and more preferably from about 700 to about 1000 g/3″ and still more preferably from about 750 to about 900 g/3″.

In a seventh embodiment the present invention provides the tissue product of any one of the first through the sixth embodiments comprising at least about 5 percent, by weight of the tissue product, Southern softwood kraft fibers.

In an eighth embodiment the present invention provides the tissue product of any one of the first through the seventh embodiments comprising Southern softwood kraft fibers having a coarseness less than about 21 mg/100 m, such as from about 17 to about 21, and a fiber length greater than about 2.2 mm.

In a ninth embodiment the present invention provides the tissue product of any one of the first through the eighth embodiments wherein the tissue product comprises less than about 5 percent, by weight of the tissue product, NSWK fibers.

In a tenth embodiment the present invention provides the tissue product of any one of the first through the ninth embodiments wherein the tissue product is substantially free from NSWK fibers.

In an eleventh embodiment the present invention provides the tissue product of any one of the first through the tenth embodiments wherein the tissue product has a CD Stretch from about 4.0 to about 6.0.

In a twelfth embodiment the present invention provides the tissue product of any one of the first through the eleventh embodiments wherein the tissue product has a CD TEA from about 3.5 to about 5.0 g·cm/cm².

In a thirteenth embodiment the present invention provides the tissue product of any one of the first through the twelfth embodiments wherein the tissue product has a CD Tear from about 10 to about 12 grams.

In a fourteenth embodiment the present invention provides the tissue product of any one of the first through the thirteenth embodiments wherein the tissue product consists essentially of EWHK and SSWK and has a basis weight less than about 20 gsm, such as from about 10 to about 20 gsm.

In a fifteenth embodiment the present invention provides the tissue product of any one of the first through the fourteenth embodiments wherein the tissue product has a PPF value greater than about 32 and a C5 value greater than about 16.

In a sixteenth embodiment the present invention provides a wet pressed tissue product comprising at least one multi-layered tissue web comprising a first and a second layer, the second layer consisting essentially of low-coarseness SSWK fibers, the tissue product having a CD Durability Index greater than about 14.0, such as from about 14.0 to about 20.0 and more preferably from about 15.0 to about 18.0, and a TS7 value less than about 20.0 dB V2 rms, such as from about 18.0 to about 20.0 dB V2 rms.

In a seventeenth embodiment the present invention provides the wet pressed tissue product of the sixteenth embodiment wherein the tissue product has a basis weight less than about 20 gsm, such as from about 10 to about 20 gsm and CD Tensile greater than about 400 g/3″.

In an eighteenth embodiment the present invention provides a multi-ply tissue product comprising at least one wet pressed tissue ply having a TS7 value less than about 20.0 dB V2 rms, a CD Tensile strength greater than about 400 g/3″ and a CD Durability Index greater than about greater than about 14.0, more preferably greater than about 14.5 and still more preferably greater than about 15.0, such as from about 14.0 to about 20.0.

In a nineteenth embodiment the present invention provides the tissue product of the eighteenth embodiment wherein the least one wet pressed tissue ply has a Burst Index greater than about 5.0.

In a twentieth embodiment the present invention provides the tissue product of the eighteenth or the nineteenth embodiments wherein the least one wet pressed tissue ply has a CD TEA Index greater than about 6.0.

In a twenty-first embodiment the present invention provides the tissue product of any one of the eighteenth through twentieth embodiments having a CD Durability Index greater than about 15.0 and a TS7 value from about 18.0 to about 20.0 dB V2 rm.

In a twenty second embodiment the present invention provides the tissue product of any one of the eighteenth through twenty-first embodiments having a GMT from about 700 to about 1200 g/3″ and more preferably from about 700 to about 1000 g/3″ and still more preferably from about 750 to about 900 g/3″ and a basis weight greater than about 30 gsm 

1. A single ply wet pressed tissue product having a TS7 value less than about 20.0 dB V2 rms a CD Tensile strength greater than about 400 g/3″ and a CD Durability Index greater than about 14.0.
 2. The tissue product of claim 1 having a Burst Index greater than about 5.0.
 3. The tissue product of claim 1 having a CD TEA Index greater than about 6.0.
 4. The tissue product of claim 1 having a CD Durability Index greater than about 15.0 and a CD Tensile strength from about 400 to about 600 g/3″.
 5. The tissue product of claim 1 wherein the TS7 value is from about 18.0 to about 20.0 dB V2 rms.
 6. The tissue product of claim 1 having a GMT from about 700 to about 1200 g/3″ and a basis weight from about 15 to about 20 gsm.
 7. The tissue product of claim 1 comprising at least about 5 percent, by weight of the tissue product, Southern softwood kraft fibers.
 8. The tissue product of claim 1 comprising at least about 5 percent, by weight of the tissue product, Southern softwood kraft fibers having a coarseness less than about 21 mg/100 m, such as from about 17 to about 21, and a fiber length greater than about 2.2 mm.
 9. The tissue product of claim 1 comprising less than about 5 percent, by weight of the tissue product, NSWK fibers.
 10. The tissue product of claim 1 wherein the tissue product is substantially free from NSWK fibers.
 11. The tissue product of claim 1 having a CD Stretch from about 4.0 to about 6.0.
 12. The tissue product of claim 1 consisting essentially of EWHK and SSWK and having a basis weight from about 10 to about 20 gsm.
 13. A single ply wet pressed tissue product having improved formation the product comprising at least about 20 percent, by weight of the product, SSWK and having a TS7 value less than about 20.0 dB V2 rms and a CD Durability Index greater than about 14.0 wherein the PPF value is greater than a comparable tissue substantially free from SSWK.
 14. The tissue product of claim 13 having a Burst Index greater than about 5.0.
 15. The tissue product of claim 13 having a CD TEA Index greater than about 6.0.
 16. The tissue product of claim 13 having a GMT from about 700 to about 1200 g/3″ and a basis weight from about 15 to about 20 gsm.
 17. A wet pressed tissue product comprising at least one multi-layered tissue web comprising a first and a second layer, the second layer consisting essentially of low-coarseness SSWK fibers, the tissue product having a CD Durability Index greater than about 14.0 and a TS7 value less than about 20.0 dB V2 rms.
 18. The tissue product of claim 17 having a basis weight less than about 20 gsm and CD Tensile from about 400 to about 600 g/3″.
 19. The tissue product of claim 17 having a Burst Index greater than about 30, a CD TEA Index greater than about 6.5 and a GMT from about 600 to about 1000 g/3″.
 20. The tissue product of claim 17 comprising at least about 5 percent, by weight of the tissue product, Southern softwood kraft fibers having a coarseness less than about 21 mg/100 m and a fiber length greater than about 2.2 mm. 